Test procedures for voltage and capacity of lithium-ion batteries

Lithium-ion battery voltage, capacity, internal resistance and pulse test procedures In order to understand the characteristics of lithium-ion batteries, this paper selects lithium iron phosphate batteries to conduct a series of experiments. Lithium iron phosphate batteries are currently considered to be the best-performing lithium-ion batteries with a wide range of applications. The experiment uses 3.2v/12.5ah single lithium ion battery, and the specific parameters are shown in Table 1. This type of lithium iron phosphate battery belongs to the power lithium battery, which is mainly used in the field of electric tools and energy storage power sources. Because it can be used under complex working conditions, it is a representative lithium-ion battery. Table 1 The name of the conventional battery indicators and specifications. Battery-type power lithium-ion battery rated capacity 12.5 ah rated voltage 3.2v weight 353g+/-0.05v maximum charging current 2C (continuous) 4C (10s) charging voltage: 3.65v±0.5v maximum discharge Current 4C (continuous) 6C (30s) discharge termination voltage 2.0v, charging temperature 0~45℃, exhaust temperature -20~60℃; the composition of the test system The characteristic test of lithium-ion battery is based on the battery test platform. The important purpose of battery testing is to have a more comprehensive understanding and quantification of battery performance, and to establish data support and theoretical basis for the study of battery characteristics. The battery test platform is shown in Figure 2. The equipment used is: lithium iron phosphate battery, Digatron automatic charge and discharge test equipment and host computer. The Digatron automatic charge and discharge test equipment tests the charge and discharge state of the battery. The host computer communicates with the Digatron automatic charge and discharge test equipment, sets the working status of the equipment, records time, voltage, current and other data, and processes and analyzes the collected data. All battery tests in this article are carried out at room temperature. Figure 2 Battery test platform Figure 2 During the charge and discharge process of the battery test platform, the working current of the battery is usually represented by the charge-discharge ratio, which is a multiple of the battery's rated capacity in value. Ensure that the battery is fully charged. The charging system is specified as follows: the first time the battery is charged with a constant current (1/3c) of 3.65v, then the charge is at a constant voltage of 3.65v until the current is less than 0.033 degrees, and then the charging is stopped in 10 minutes and let it represent 1h. The battery experiment designed in this paper refers to the national industry standard QC/t743-2006 [5]. The specific experiment content is as follows: Capacity test In order to measure the actual capacity of lithium-ion batteries at different discharge rates, the test discharge rates are controlled as Iu003d{0.2C,0.5C,1.0C,1.5C,2.0C}. Each test is carried out according to the following five steps: The first step: charge the battery. The second step: stand for one hour. The third step: discharge with I as the discharge rate. Stop discharging when the battery voltage reaches 2.0V. Step 4: When the test is over after standing for one hour, use a small current of 0.02c to discharge the battery. The open circuit voltage characteristic test is to test the difference between the discharging process and the charging process of the lithium-ion battery. The electromotive force of the remaining capacity divides the test into a discharge process and a charging process. The discharge process test is carried out according to the following steps: Step 1: Charge the battery Step 2: Stand for one hour Step 3. Discharge at a constant discharge rate of 1/3c for 18 minutes; if the battery voltage is lower than 2.0v within 18 minutes, go to step 5; otherwise, go to step 4. Step 4. Let it rest for an hour, and then return to the third step. At the end of the test, use a small current of 0.02c to discharge the battery. The charging process is tested as follows: Step 1: Empty the battery Step 2: Stand for one hour Step 3. The discharge rate is 1/3c, and the battery continues to discharge for 18 minutes. If the battery voltage is higher than 3.6v within 18 minutes, go to step 5; otherwise, go to step 4. Step 4. Let it rest for an hour, and then go back to step 3 and step 5. After the test is over, charge the battery. Statement: Some pictures and content of the articles published on this site are from the Internet. If there is any infringement, please contact to delete. Previous: Summary of the advantages and disadvantages of lithium-ion battery performance